Fluid pump mechanical seal

ABSTRACT

A fluid pump having a pump motor, pump housing, and pump seal enclosure disposed between the pump motor and the pump housing. A pump drive shaft is rotatably driven by the pump motor and extends through the pump seal enclosure and a drive shafting opening into a pumping chamber of the pump housing. A drive shaft seal assembly is disposed within the pump seal enclosure and includes a spring seat, rotary ring, stationary ring, and compressible spring each disposed coaxially with the drive shaft. The spring seat includes a first alignment mechanism and the rotary ring includes a second alignment mechanism for engaging the first alignment mechanism. The stationary ring is fastened to the pump seal enclosure adjacent the drive shaft opening, and the compressible spring biases the rotary ring against the stationary ring.

CROSS-REFERENCE TO RELATED APPLICATION

This application claims priority to U.S. Provisional Application Ser.No. 61/443,826 filed Feb. 17, 2011, and entitled “Fluid Pump MechanicalSeal,” incorporated by reference herein in its entirety.

FIELD

This disclosure relates to the field of fluid pumps. More particularly,this disclosure relates to an improved drive shaft mechanical seal forpumps such as gear pumps.

BACKGROUND

A variety of fluid displacement pumps are known and are well suited to avariety of pumping applications. In particular, gear pumps are known tobe used in fluid applications requiring precise metering or dosingcapabilities because the volume and flow rate of the liquid supplied bythe gear pump is based upon the rate of rotation of the gears. Typicalgear pumps include a pump housing and a pair of intermeshing gearsdisposed within an internal pumping chamber within the housing. Inputand output ports are located on opposing sides of the pump housing.During operation, a drive gear is driven by a drive shaft which in turnrotates an idler gear. The fluid being pumped is primarily carried fromthe input port through the internal pumping chamber and the spacesdisposed between adjacent idler teeth to the output port.

It is known to prevent leakage of the liquids being pumped in thepumping chamber using a mechanical seal attached to the drive shaftadjacent the pump housing. However, prior art pumps have had problemskeeping the pumped fluids out of the seal enclosure of the mechanicalseal as the natural inclination of the fluid is to go from the highpressure area of the internal pumping chamber to the low pressure areaof the seal enclosure. Especially in sanitary applications, such aspumping liquids for use in carbonated water systems and espresso andcappuccino machines, this is highly undesirable. Similar sanitationconcerns may apply to pumps intended for medical applications as well.What is needed is a mechanical seal that prevents pumped fluids fromentering the pump seal enclosure during normal operation of the pump.

SUMMARY OF THE INVENTION

According to certain embodiments, the present disclosure provides afluid pump having a pump motor, a pump housing, and a pump sealenclosure. The pump housing includes an internal pumping chamber, asuction orifice in flow communication with the pumping chamber, adischarge orifice in flow communication with the pumping chamber, and adrive shaft opening. The pump seal enclosure is disposed between thepump motor and the pump housing. A pump drive shaft is rotatably drivenby the pump motor and extends through the pump seal enclosure and thedrive shafting opening into the pumping chamber. A drive shaft sealassembly is disposed within the pump seal enclosure. The drive shaftseal assembly includes a spring seat fastened to the drive shaft, thespring seat being disposed coaxially with the drive shaft and adjacentthe pump motor and further having a first alignment mechanism, a rotaryring disposed coaxially with the drive shaft and having a secondalignment mechanism for engaging the first alignment mechanism of thespring seat, a stationary ring disposed coaxially with the drive shaftand fastened to the pump seal enclosure adjacent the drive shaftopening, and a compressible spring disposed coaxially with the driveshaft between the spring seat and the rotary ring, wherein the springbiases the rotary ring against the stationary ring.

In certain embodiments, the spring seat is fastened to the drive shaftby at least one set screw. A washer may be disposed coaxially with thedrive shaft and adjacent the stationary ring, and the washer andstationary ring are non-rotatably fastened to the pump seal enclosure byat least one set screw. An O-ring may also be disposed between thestationary ring and the pump housing.

In certain embodiments, the draft seal assembly causes substantially nopumped fluids to enter the pump seal enclosure during normal operationof the pump. Also, substantially no pumped fluids contact the springseat, the compressible spring, or the rotary ring during normaloperation of the pump.

In some embodiments, the stationary ring comprises one of a ceramicmaterial and a silicon carbide material and the rotary ring comprises agraphite material. The first alignment mechanism of the spring seatincludes may includes at least one alignment rib and the secondalignment mechanism of the rotary ring includes at least one slot forreceiving and engaging the at least one alignment rib.

According to another embodiment of the disclosure, a fluid gear pump isdisclosed having a pump motor, a pump housing, and a pump sealenclosure. The pump housing includes an internal pumping chamber, asuction orifice in flow communication with the pumping chamber, adischarge orifice in flow communication with the pumping chamber, and adrive shaft opening. The pump seal enclosure is disposed between thepump motor and the pump housing. A pump drive shaft is rotatably drivenby the pump motor and extends through the pump seal enclosure and thedrive shafting opening into the pumping chamber. A drive gear, having aplurality of drive gear teeth, is disposed within the pumping chamberand is rotatably driven by the drive shaft. An idler gear, having aplurality of idler gear teeth intermeshed with the drive gear teeth, isdisposed within the pumping chamber and attached to an idler shaftdisposed within the pumping chamber. A drive shaft seal assembly isdisposed within the pump seal enclosure. The drive shaft seal assemblyincludes a spring seat fastened to the drive shaft, the spring seatbeing disposed coaxially with the drive shaft and adjacent the pumpmotor and further having a first alignment mechanism, a rotary ringdisposed coaxially with the drive shaft and having a second alignmentmechanism for engaging the first alignment mechanism of the spring seat,a stationary ring disposed coaxially with the drive shaft and fastenedto the pump seal enclosure adjacent the drive shaft opening, and acompressible spring disposed coaxially with the drive shaft between thespring seat and the rotary ring, wherein the spring biases the rotaryring against the stationary ring.

In certain embodiments, the spring seat is fastened to the drive shaftby at least one set screw. A washer is disposed coaxially with the driveshaft and adjacent the stationary ring, and the washer and stationaryring are non-rotatably fastened to the pump seal enclosure by at leastone set screw. An O-ring is disposed between the stationary ring and thepump housing.

In certain embodiments according to the present disclosure,substantially no pumped fluids enter the pump seal enclosure duringnormal operation of the pump. Also, substantially no pumped fluidscontact the spring seat, the compressible spring, or the rotary ringduring normal operation of the pump.

According to some embodiments of the disclosure, the stationary ringcomprises one of a ceramic material and a silicon carbide material andthe rotary ring comprises a graphite material.

In some embodiments the first alignment mechanism of the spring seatincludes at least one alignment rib and the second alignment mechanismof the rotary ring includes at least one slot for receiving and engagingthe at least one alignment rib.

BRIEF DESCRIPTION OF THE DRAWINGS

Further advantages of the invention are apparent by reference to thedetailed description when considered in conjunction with the figures,which are not to scale so as to more clearly show the details, whereinlike reference numbers indicate like elements throughout the severalviews, and wherein:

FIG. 1 is a cross-sectional side view of a fluid gear pump according toone embodiment of the present disclosure;

FIG. 2 is a cross-sectional front view of a fluid gear pump according toone embodiment of the present disclosure illustrating the internalpumping chamber;

FIG. 3 is a cross-sectional view side view of a pump housing and pumpseal enclosure according to one embodiment of the present disclosure;and

FIG. 4 is an exploded view of a drive shaft seal assembly according toone embodiment of the present disclosure.

DETAILED DESCRIPTION

According to one embodiment of the present disclosure, a fluid pump 10is provided. The fluid pump 10 according to the present disclosure issuitable for pumping a wide variety of liquids. The fluid pump 10 isparticularly suited for pumping liquids for use in beverages, such asfor pumping liquids in carbonated water systems, for espresso andcappuccino machines, and for beer cooling systems.

As may be seen in FIG. 1, the fluid pump 10 includes a motor 12. Thepump motor 12 is preferably an electric motor; however, the pump motor12 may alternatively be powered by other means such as by internalcombustion. A pump drive shaft 14 is attached to the pump motor 12 anddriven thereby. The pump drive shaft 14 is preferably made from a metalsuch as steel.

The fluid pump 10 includes a pump assembly 16 having a pump housing 18and a pump seal enclosure 20 disposed between the pump motor 12 and pumphousing 18. The pump seal enclosure 20 is preferably readily removablefrom the pump housing 18 for pump disassembly and cleaning The pumpdrive shaft 14 extends through the pump seal enclosure 20 into the pumphousing 18 for driving the pump assembly 16. While it should beunderstood that the mechanical seal assembly of the present disclosuremay be used in connection with numerous types of fluid displacement pumpsuch as a gear pump, vane pump, centrifugal pumps, etc., the mechanicalseal assembly of the present disclosure, as shown and described in theexemplary embodiments herein, is preferably used with a gear pump.

With further reference to FIGS. 1-2, the pump housing 18 is preferablyoval shaped and includes an internal pumping chamber 22, a suctionorifice 24 in flow communication with the pumping chamber 22, and adischarge orifice 26 in flow communication with the pumping chamber 22.The pump housing 18 further includes a drive shaft opening 28 throughwhich the drive shaft 14 extends into the pump housing 18. A drive gear30, having a plurality of drive gear teeth 31, is disposed within thepumping chamber 22 and is operable to be rotatably driven by the driveshaft 14. An idler gear 32, having a plurality of idler gear teeth 33operable to be intermeshed with the drive gear teeth 31 so that theidler gear 32 is rotatable when the drive gear 30 is driven by the driveshaft 14, is also disposed within the pumping chamber 22 and is attachedto an idler shaft 36 disposed within the pumping chamber 22.

During operation of the gear pump, the drive shaft 14 rotates the drivegear 30 which in turn rotates the idler gear 32. As the drive gear teeth31 come out of mesh with the idler gear teeth 33, the teeth 31 and 33create expanding volume on the suction orifice 24. Liquid flows into thesuction orifice 24 and is trapped by the gear teeth 31 and 33 as theyrotate. Liquid then travels around the interior of the pumping chamber22 until it is forced out through the discharge orifice 26 at a greaterpressure than when the liquid flowed into the suction orifice 24. Thesuction orifice 24 and discharge orifice 26 are interchangeabledepending on the direction of rotation of the drive gear 30 and idlergear 32.

The pump housing 18 is generally formed from a high strength material.In certain embodiments, the pump housing 18 is preferably formed of ametal such as brass or stainless steel; however, in other embodiments,the pump housing 18 is preferably made from a high strength plasticmaterial. More preferably, the pump housing 18 is made from an injectionmolded plastic material. The plastic material may be reinforced withfibers such as glass fibers for added strength.

The pump seal enclosure 20 is generally formed from a high strengthmaterial. In certain embodiments, the pump seal enclosure 20 ispreferably formed of stainless steel, carbon, or silicon carbide.However, these and other materials may be used and are often dependenton the particular fluids being pumped through the pump assembly 16.

In accordance with the present disclosure, the drive shaft opening 28 issealed by a drive shaft seal assembly 34 disposed within the pump sealenclosure 20. Referring to FIGS. 3-4, the drive shaft seal assembly 34includes a spring seat 36 disposed adjacent the pump motor 12, astationary ring 50 disposed adjacent the pump housing 18, and a rotaryring 44 disposed between the spring seat 36 and the stationary ring 50.Each of the spring seat 36, rotary ring 44, and stationary ring 50 aredisposed coaxially with the drive shaft 14. The spring seat 36 isfastened to the drive shaft 14 adjacent the pump motor using at leastone set screw 38, or other known attachment mechanisms. The spring seat36 includes at least one first alignment mechanism 40 attached to thespring seat 36 for engaging a corresponding second alignment mechanism46 attached to the rotary ring 44 for coupling the spring seat 36 withthe rotary ring 44. In preferred embodiments, the first alignmentmechanism 40 is an alignment rib disposed on an outer surface 42 of thespring seat 36 and the second alignment mechanism 46 is a slot disposedwithin an outer surface 48 of the rotary ring 44 for receiving thealignment rib 40 of the spring seat 36. The stationary ring 50 isattached to the pump seal enclosure 20 adjacent the drive shaft opening28 using at least one set screw 52, or other known attachmentmechanisms. A compressible spring 54 is also disposed coaxially with thedrive shaft 14 between the spring seat 36 and the rotary ring 44 forbiasing the rotary ring 44 against the stationary ring 50.

The drive shaft seal assembly 34 may include a washer 56 disposedbetween the stationary ring 50 and the rotary ring 44. Washer 56 ispreferably also fixed to the pump seal enclosure using set screws 52.The drive shaft seal assembly 34 may also include an O-ring 58 disposedbetween the stationary ring 50 and the pump housing 18 for furthersealing the drive shaft seal assembly 34 against the pump housing 18.

As the stationary ring 50 is attached to the pump seal enclosure 20, thestationary ring 50 is fixed and does not rotate in conjunction with thedrive shaft 14 during operation of the pump 10. Accordingly, thestationary ring 50, and O-ring 58 if present, prevents pumped fluidsfrom entering the pump seal enclosure 20 during normal operation of thepump 10. Thus, substantially no pumped fluids contact the spring seat36, the compressible spring 54, or the rotary ring 44 during normaloperation of the pump. This design results in a fluid pump operable tobe used in sanitary applications because fewer parts of the pump are incontact with the fluid flow path, and the design reduces the amount ofliquid waste when the pump is being flushed for cleaning.

While the stationary ring 50 is fixed to the pump seal enclosure 20 sothat the stationary ring 50 does not rotate during operation of the pump10, the spring seat 36 is attached to and rotates with the drive shaft14. Because the rotary ring 44 is coupled with the spring seat 36, therotary ring 44 also rotates in conjunction with the spring seat 36 anddrive shaft 14. Due to the friction caused by the rotary ring 44 beingbiased against the stationary ring 50, the stationary ring 50 ispreferably composed of a ceramic material while the rotary ring 44 iscomposed of a graphite material.

The foregoing description of preferred embodiments for this inventionhave been presented for purposes of illustration and description. Theyare not intended to be exhaustive or to limit the invention to theprecise form disclosed. Obvious modifications or variations are possiblein light of the above teachings. The embodiments are chosen anddescribed in an effort to provide the best illustrations of theprinciples of the invention and its practical application, and tothereby enable one of ordinary skill in the art to utilize the inventionin various embodiments and with various modifications as are suited tothe particular use contemplated. All such modifications and variationsare within the scope of the invention as determined by the appendedclaims when interpreted in accordance with the breadth to which they arefairly, legally, and equitably entitled.

1. A fluid pump comprising: a pump motor; a pump housing having aninternal pumping chamber, a suction orifice in flow communication withthe pumping chamber, a discharge orifice in flow communication with thepumping chamber, and a drive shaft opening; a pump seal enclosuredisposed between the pump motor and the pump housing; a pump drive shaftrotatably driven by the pump motor and extending through the pump sealenclosure and the drive shafting opening into the pumping chamber; and adrive shaft seal assembly disposed within the pump seal enclosure, thedrive shaft seal assembly including: a spring seat fastened to the driveshaft, the spring seat being disposed coaxially with the drive shaft andadjacent the pump motor and further having a first alignment mechanism,a rotary ring disposed coaxially with the drive shaft and having asecond alignment mechanism for engaging the first alignment mechanism, astationary ring disposed coaxially with the drive shaft and fastened tothe pump seal enclosure adjacent the drive shaft opening, and acompressible spring disposed coaxially with the drive shaft between thespring seat and the rotary ring, wherein the spring biases the rotaryring against the stationary ring.
 2. The fluid pump of claim 1, whereinthe spring seat is fastened to the drive shaft by at least one setscrew.
 3. The fluid pump of claim 1, further comprising a washerdisposed coaxially with the drive shaft and adjacent the stationaryring.
 4. The fluid pump of claim 3, wherein the washer and stationaryring are non-rotatably fastened to the pump seal enclosure by at leastone set screw.
 5. The fluid pump of claim 1, further comprising anO-ring disposed between the stationary ring and the pump housing.
 6. Thefluid pump of claim 1, wherein substantially no pumped fluids enter thepump seal enclosure during normal operation of the pump.
 7. The fluidpump of claim 1, wherein substantially no pumped fluids contact thespring seat, the compressible spring, or the rotary ring during normaloperation of the pump.
 8. The fluid pump of claim 1, wherein thestationary ring comprises a ceramic material.
 9. The fluid pump of claim1, wherein the rotary ring comprises a graphite material.
 10. The fluidpump of claim 1, wherein the first alignment mechanism of the springseat includes at least one alignment rib and the second alignmentmechanism of the rotary ring includes at least one slot for receivingand engaging the at least one alignment rib.
 11. A fluid gear pumpcomprising: a pump motor; a pump housing having an internal pumpingchamber, a suction orifice in flow communication with the pumpingchamber, a discharge orifice in flow communication with the pumpingchamber, and a drive shaft opening; a pump seal enclosure disposedbetween the pump motor and the pump housing; a pump drive shaftrotatably driven by the pump motor and extending through the pump sealenclosure and the drive shafting opening into the pumping chamber; adrive gear, having a plurality of drive gear teeth, disposed within thepumping chamber and rotatably driven by the drive shaft; an idler gear,having a plurality of idler gear teeth intermeshed with the drive gearteeth, disposed within the pumping chamber and attached to an idlershaft disposed within the pumping chamber; and a drive shaft sealassembly including: a spring seat fastened to the drive shaft, thespring seat being disposed coaxially with the drive shaft and adjacentthe pump motor and further having a first alignment mechanism, a rotaryring disposed coaxially with the drive shaft and having a secondalignment mechanism for engaging the first alignment mechanism of thespring seat, a stationary ring disposed coaxially with the drive shaftand fastened to the pump seal enclosure adjacent the drive shaftopening; and a compressible spring disposed coaxially with the driveshaft and between the spring seat and the rotary ring, wherein thespring biases the rotary ring against the stationary ring.
 12. The fluidgear pump of claim 11, wherein the spring seat is fastened to the driveshaft by at least one set screw.
 13. The fluid gear pump of claim 11,further comprising a washer disposed coaxially with the drive shaft andadjacent the stationary ring.
 14. The fluid gear pump of claim 13,wherein the washer and stationary ring are non-rotatably fastened to thepump seal enclosure by at least one set screw.
 15. The fluid gear pumpof claim 11, further comprising an O-ring disposed between thestationary ring and the pump housing.
 16. The fluid gear pump of claim11, wherein substantially no pumped fluids enter the pump seal enclosureduring normal operation of the pump.
 17. The fluid gear pump of claim11, wherein substantially no pumped fluids contact the spring seat, thecompressible spring, or the rotary ring during normal operation of thepump.
 18. The fluid gear pump of claim 11, wherein the stationary ringcomprises a ceramic material.
 19. The fluid gear pump of claim 11,wherein the rotary ring comprises a graphite material.
 20. The fluidgear pump of claim 11, wherein the first alignment mechanism of thespring seat includes at least one alignment rib and the second alignmentmechanism of the rotary ring includes at least one slot for receivingand engaging the at least one alignment rib.